In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during
Isothermal compression
Isentropic compression
Polytropic compression
None of these
Correct Answer :
A. Isothermal compression
Related Questions
Volumetric efficiency of a compressor with clearance volume
Increases with increase in compression ratio
Decreases with increase in compression ratio
In not dependent upon compression ratio
May increase/decrease depending on compressor capacity
An aftercooler is used to
Remove impurities from air
Reduce volume of air
Cause moisture and oil vapour to drop out
Cool the air
In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during
Isothermal compression
Isentropic compression
Polytropic compression
None of these
Reheating in a multistage expansion gas turbine __________ compressor work.
Has no effect on
Decreases
Increases
None of these
Gas turbine works on
Brayton or Atkinson cycle
Carnot cycle
Rankine cycle
Erricson cycle
The overall isothermal efficiency of compressor is defined as the ratio of
Isothermal h.p. to the BHP of motor
Isothermal h.p. to adiabatic h.p.
Power to drive compressor to isothermal h.p.
Work to compress air isothermally to work for actual compression
The efficiency of jet engine is
Lower at low speed
Higher at high altitudes
Same at all altitudes
Higher at high speed
A gas turbine used in air craft should have
High h.p. and low weight
Low weight and small frontal area
Small frontal area and high h.p.
High speed and high h.p
The capacity of compressor will be highest when its intake temperature is
Lowest
Highest
Anything
Atmospheric
In multistage compressor, the isothermal compression is achieved by
Employing intercooler
By constantly cooling the cylinder
By running compressor at very slow speed
By insulating the cylinder
The compressed air may be used
In gas turbine plants
For operating pneumatic drills
In starting and supercharging of I.C. engines
All of the above
The velocity of air entering in a rocket is ________ as compared to an aircraft.
Zero
Less
More
Same
In a centrifugal compressor, an increase in speed at a given pressure ratio causes
Increase in flow
Decrease in flow
Increase in efficiency
Increase in flow and decrease in efficiency
Maximum work is done in compressing air when the compression is
Isothermal
Adiabatic
Polytropic
None of the above
In a closed cycle gas turbine, the air is compressed
Isothermally
Polytropically
Isentropically
None of these
The compressor capacity with decrease in suction temperature
Increases
Decreases
Remain unaffected
May increase or decrease depending on compressor capacity
Losses in a centrifugal compressor are due to
Inlet losses
Impeller channel losses
Diffuser losses
All of the above
The efficiency of the vane blower is (where W₁ = Workdone due to compression, and W₂ = Workdone due to back flow)
W₁/(W₁ + W₂)
W₂/(W₁ + W₂)
(W₁ + W₂)/W₁
(W₁ + W₂)/W₂
A closed cycle gas turbine consists of a
Compressor
Heating chamber
Cooling chamber
All of these
Propulsive efficiency is defined as ratio of
Thrust power and fuel energy
Engine output and propulsive power
Propulsive power and fuel input
Thrust power and propulsive power
The volume of air delivered in a medium capacity air compressor per unit time is
0.1 to 1.2 m³/s
0.15 to 5 m³/s
Above 5 m³/s
None of these
The ratio of workdone per cycle to the stroke volume of the compressor is known as
Compressor capacity
Compression ratio
Compressor efficiency
Mean effective pressure
The work ratio of a gas turbine plant is defined as the ratio of
Net work output and heat supplied
Net work output and work done by turbine
Actual heat drop and isentropic heat drop
Net work output and isentropic heat drop
Reheating in multistage expansion gas turbine results in
High thermal efficiency
Reduction in compressor work
Decrease of heat loss in exhaust
Maximum work output
The air entry velocity m a rocket as compared to aircraft is
Same
More
Less
Zero
High air-fuel ratio in gas turbines
Increases power output
Improves thermal efficiency
Reduces exhaust temperature
Do not damage turbine blades
Diffuser in a compressor is used to
Increase velocity
Make the flow streamline
Convert pressure energy into kinetic energy
Convert kinetic energy into pressure energy
Free air is the air at
Atmospheric conditions at any specific location
20°C and 1 kg/cm² and relative humidity of 36%
0°C and standard atmospheric conditions
15°C and 1 kg/cm²
The compression ratio for the compressor is always __________ unity.
Equal to
Less than
More than
None of these
Phenomenon of choking in compressor means
No flow of air
Fixed mass flow rate regardless of pressure ratio
Reducing mass flow rate with increase in pressure ratio
Increased inclination of chord with air steam